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www.cdc.gov/flu
Daniel B. Jernigan, MD MPHDaniel B. Jernigan, MD MPHDeputy Director, Influenza DivisionDeputy Director, Influenza Division
National Center for Immunization and Respiratory DiseasesNational Center for Immunization and Respiratory Diseases
Surveillance in a Pandemic:Surveillance in a Pandemic:Situational Awareness Situational Awareness and Assessing Severityand Assessing Severity
www.cdc.gov/flu
Objectives
Describe the US experience with surveillance and situational awareness during the 2009 pandemic
Identify some things that worked and some that could be improved
Describe the challenges of measuring severity in an emerging pandemic
www.cdc.gov/flu
First Cases Prompt
Investigation April 21 report of two cases in Southern California Both cases seen as outpatients, both recovered April 24 report of link with cases in Mexico
Same virus, different sense of “severity” or potential impact
Cases prompted a cascade of activity Enhanced surveillance Virus characterization
MMWR
www.cdc.gov/flu
CDC Virologic Surveillance in the First Week
0
2000
4000
6000
8000
10000
12000
Week Number
Num
ber
of
Posi
tive S
peci
mens
0
10
20
30
40
50
60
70
80
90
100
Perc
ent
Posi
tive
B A(Subtyping not performed) A(H1)
A(H3) A(Unable to Subtype) A(2009 H1N1)
Percent Positive
2008 2009
35,000Specimens Tested in One Week
196,000Specimens
Tested Over the Season
www.cdc.gov/flu
April 27CDC posts 40 gene
sequences on
GenBank
May 1First Diagnostic Kits Shipped toWHO Network and State Labs
To date: 2,125 kits to 432 labs in 142 Countries
May 7Case Series (N=642)
Published in NEJM
May 23Vaccine Strain
Begins Shipping toManufacturers
April 28CDC Posted PCR
Protocol on
WHO website
Virus
DetectedField Investigations and Enhanced Surveillance
Early Assessment
www.cdc.gov/flu
Early Estimate of Symptomatic Case Fatality RatioReed, Biggerstaff – CDC unpublished data
www.cdc.gov/flu
Making Situational Awareness Possible in the First Days
Early communication accelerated global response
Case-contact investigations and community surveys were critical for early characterization
Availability of diagnostics aided response PCR devices in place or quickly deployed Influenza Reagent Resource for distribution
Preparedness investments invaluable
www.cdc.gov/flu
Early Challenges Decisions need to be made on limited data
Estimating and monitoring impact is an ongoing process
Need to manage expectations of stakeholders and decision-makers
Pandemic planning called for severity estimates based on mortality alone; however, may not be available may not reflect the potential impact of the pandemic are difficult to maintain with lab-confirmation
www.cdc.gov/flu
Pandemic Severity Index Benchmarked to Past Pandemic Mortality
www.cdc.gov/flu
During the Summer
www.cdc.gov/flu
CDC Virologic Surveillance During the Summer Months
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Week Number
Num
ber
of
Posi
tive S
peci
mens
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80
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100
Perc
ent
Posi
tive
B A(Subtyping not performed) A(H1)
A(H3) A(Unable to Subtype) A(2009 H1N1)
Percent Positive
2008 2009
ILI visits greatly increased above baseline Notably in younger patients
Hospitalization rates point to increases in younger patients
PCR-confirmed case counting stopped
www.cdc.gov/flu
On Arrival at CampCabin has 25 Campers
Situational Awareness from CampersA Personal Account
www.cdc.gov/flu
On Arrival at CampCabin has 25 Campers
One Week LaterCabin has 11 Campers
Situational Awareness from CampersA Personal Account
www.cdc.gov/flu
Observations from the Summer Existing laboratory and epidemiologic infrastructure
critical for sustained surge New surveillance activities initiated
Aggregate hospitalization and deaths reporting Reports from electronic health records
Serologic studies helpful for indicating immunity in older individuals need more automated and rapid testing capacity
Uncertainty of potential changes in the virus required maintained vigilance and planning
www.cdc.gov/flu
Through the Fall Wave
www.cdc.gov/flu
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Week Number
Num
ber
of
Posi
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mens
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10
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40
50
60
70
80
90
100
Perc
ent
Posi
tive
B A(Subtyping not performed) A(H1)
A(H3) A(Unable to Subtype) A(2009 H1N1)
Percent Positive
2008 2009
CDC Virologic Surveillance through the Fall Wave
www.cdc.gov/flu
Clinics & ED’s
Hospital
Death
Assessing “severity” or “influenza impact” was accomplished using surveillance data to monitor morbidity and
mortality to compare with prior
seasons to estimate numbers of
cases
www.cdc.gov/flu
Visits for ILI surpassed prior seasons, notably among younger age groups
0
1
2
3
4
5
6
7
8
9
10/7
/06
12/2
/06
1/27
/07
3/24
/07
5/19
/07
7/14
/07
9/8/
07
11/3
/07
12/2
9/07
2/23
/08
4/19
/08
6/14
/08
8/9/
08
10/4
/08
11/2
9/08
1/24
/09
3/21
/09
5/16
/09
7/11
/09
9/5/
09
10/3
1/09
12/2
6/09
2/20
/10
4/17
/10
6/12
/10
8/7/
10
Week
% o
f V
isits
for
ILI
% ILI National Baseline
2006-07
2007-08
2008-09
2009-10
Schools Start
www.cdc.gov/flu
2009 H1N1 Hospitalizations varied by age and differed from previous seasons
CDC Emerging Infections Program
* Pan H1N1 is for data from Sep 1, 2009 to Jan 21, 2010
www.cdc.gov/flu
Pneumonia and Influenza Mortality for 122 U.S. CitiesAggregate data does not represent impact on those <65
4
6
8
10
50 10 20 30 40 50 10 20 30 40 50 10 20 30 40 50 10 20 30 40 50 10 20
Weeks
% o
f A
ll D
eath
s D
ue t
o P
&I
2006-07 2007-08 2008-09 2009-102005-06
FallWave
H3N2
www.cdc.gov/flu
Number of Influenza-Associated Laboratory-Confirmed Pediatric Deaths
0
5
10
15
20
25
30
35
2007-4
0
2007-4
6
2007-5
2
2008-0
6
2008-1
2
2008-1
8
2008-2
4
2008-3
0
2008-3
6
2008-4
2
2008-4
8
2009-0
1
2009-0
7
2009-1
3
2009-1
9
2009-2
5
2009-3
1
2009-3
7
2009-4
3
2009-4
9
2010-0
3
Week of Death
Nu
mb
er
of
de
ath
s
2007-08
88 Pediatric Deaths
2008-09
69 Pediatric Deaths
www.cdc.gov/flu
Number of Influenza-Associated Laboratory-Confirmed Pediatric Deaths
0
5
10
15
20
25
30
35
20
07
-40
20
07
-46
20
07
-52
20
08
-06
20
08
-12
20
08
-18
20
08
-24
20
08
-30
20
08
-36
20
08
-42
20
08
-48
20
09
-01
20
09
-07
20
09
-13
20
09
-19
20
09
-25
20
09
-31
20
09
-37
20
09
-43
20
09
-49
20
10
-03
Week of Death
Nu
mb
er
of
de
ath
s
2007-08
88 Pediatric Deaths
2008-09
69 Pediatric Deaths
Since H1N1
344 Pediatric Deaths
4 – 5 times more than
prior seasons
www.cdc.gov/flu
Characteristics of 2009 H1N1 InfluenzaApril 15, 2009 to April 10, 2010
Cases61,000,000 (43M – 89M)
Hospitalizations274,000 (195K – 403K)
Deaths12,470 (8.9K – 19.3K)
0-4
5-24
25-4
9
50-6
4
≥65
App
roxi
mat
e R
ate
per
100,
000
popu
latio
n
www.cdc.gov/flu
Assessing Severity Assessments
Mortality alone does not reflect the full pandemic impact 90% of deaths generally among >65 yos For H1N1, 90% among <65 yos Lab-confirmed cases underreported Estimates of years of potential life lost range
334K to 1.2M (Viboud PLoS Curr Influenza 2010)
Many difficult decisions need to be made early when limited data may be available
www.cdc.gov/flu
Next Steps for Severity Assessment
Efforts underway at WHO to identify new approach to severity assessment
CDC gathering input on a new framework drafted by Reed and Biggerstaff which allows for: Data collection from early virologic and field
investigations, as well as established systems Assesment based on categories of transmission and
clinical severity Translation of the findings into context- appropriate
recommendations
www.cdc.gov/flu
Thank You
Acknowledgements State and Local Health Departments WHO and numerous international public health
partners CDC
Influenza Division Epidemiology and Laboratory Branches
Staff and guests assisting in the response